java: 输入 int[] 时表达式的非法开始

Question

我无法弄清楚我的输入参数有什么错误，编译错误消息没有多大帮助。

 import java.util.ArrayList;

/**
 * Created by cheun on 11/8/2017.
 */
public class Problem2_ProductsOfAllIntsExceptAtIndex {
    static int pointer;
    static int[] arr;
    static int[] temp_arr;
    static int input;

    public static int[] myFunction(int[] arg) {
        // write the body of your function here
        for (int i = 0; i <= arg.length; i++) {
            pointer = i;
            temp_arr = arg;
            temp_arr[i] = 1; // or should put it null
            for (int j = 0; i <= arr.length; i++) {
                input *= temp_arr[j];
            }
            arr[pointer] = input;
        }
        return arr;

    }

    public static void main(String[] args) {
        Problem2_ProductsOfAllIntsExceptAtIndex solution = new Problem2_ProductsOfAllIntsExceptAtIndex();
// line 32 FAULTY LINE BELOW
            System.out.println(myFunction([0, 1, 2, 3]));
// line 32 FAULTY LINE ABOVE    
        }

    }

D:\java_workspace\InterviewQuestions\com.cake.interviews\src\Problem2_ProductsOfAllIntsExceptAtIndex.java Error:(32, 39) java: illegal start of expression Error:(32, 40) java: ')' expected Error:(32, 41) java: ';' expected Error:(32, 43) java: not a statement Error:(32, 44) java: ';' expected

Answer 1

1.arr未实例化->空指针异常

2.If 你想输入一个带有数字的数组使用这个：

System.out.println(myFunction(new int[]{0, 1, 2, 3}));

或者您可以将我的函数定义更改为 myFunction(int...arg) 并给出由逗号分隔的参数

示例：

public class Problem2_ProductsOfAllIntsExceptAtIndex {
    static int pointer;
    static int[] arr= new int[4];
    static int[] temp_arr;
    static int input;

    public static int[] myFunction(int[] arg) {
        // write the body of your function here
        for (int i = 0; i <= arg.length; i++) {
            pointer = i;
            temp_arr = arg;
            temp_arr[i] = 1; // or should put it null
            for (int j = 0; i <= arr.length; i++) {
                input *= temp_arr[j];
            }
            arr[pointer] = input;
        }
        return arr;

    }

    public static void main(String[] args) {
        Problem2_ProductsOfAllIntsExceptAtIndex solution = new Problem2_ProductsOfAllIntsExceptAtIndex();
// line 32 FAULTY LINE BELOW
            System.out.println(Arrays.toString(myFunction(new int[]{0, 1, 2, 3})));
// line 32 FAULTY LINE ABOVE    
        }

    }

Answer 2

您的程序中有几处错误。我强烈建议学习 Java 语言的基础知识。互联网上有很多免费资源。这是 Java Tutorials website where you could start. And here 你可以直接转到 Java 中的数组。

话虽如此，以下可能是您想要实现的目标：

public class Problem2_ProductsOfAllIntsExceptAtIndex {

    public static int[] myFunction(int[] arg) {
        // making all variables global (=> static) doesn't make sense in this case
        int input = 1;    
        int[] temp_arr;
        int[] arr ;

        arr = new int[arg.length];
        for (int i = 0; i < arg.length; i++) {
            temp_arr = Arrays.copyOf(arg, arg.length);  // clone the original array; otherwise you overwrite the original one
            temp_arr[i] = 1; // or should put it null
            for (int j = 0; j < temp_arr.length; j++) {
                input *= temp_arr[j];
            }
            arr[i] = input;
            input = 1; // reset
        }
        return arr;

    }

    public static void main(String[] args) {
        int [] arr = myFunction(new int[] { 0, 1, 2, 3 });
        System.out.println(Arrays.toString(arr));
    }

}

java: 输入 int[] 时表达式的非法开始

java: illegal start of expression when entering int[]

java

illegalargumentexception